Newbie doesn't quite understand Est. Max Lift Weight in Estes Rocket Engine Performance Chart

[jrap330]

I received my new "drug user" edition of digital scale yesterday. Upon weighing my Baffled Big Bertha - and contrary to the 4.9 oz figure reported on my old mechanical scales - I now get a new figure of 4.6 oz, with B6-2 motor and 7"x100" streamer. Even though this is slightly over the Est. Max Lift Weight, I plan to risk a launch with this motor.

why s streamer on marginal B6 launch bertha find break do to swept back, use a 12 inch chute, she is not flying high. I used a 12 inch and 12 inch spill hole and have 2 crack fins so streamer is pushing it for safe landing. C6 or C5 yeah maybe streamer.

 

[jrap330]

Forget my list, just read about your fin redesign

 

[Dotini]

I've pleated my streamers, and am now contemplating the attachment method. The simplest seems to be a knotted line held in tape going out one side. I've seen another with a taped on soda straw providing for a line going out both sides. Any preference?

Questions: Does my mylar streamer need wadding, or does my baffle satisfy that requirement? When not in use, should the streamer be stored in the tightly pleated condition, or in the expanded condition?

 

[BABAR]

I've pleated my streamers, and am now contemplating the attachment method. The simplest seems to be a knotted line held in tape going out one side. I've seen another with a taped on soda straw providing for a line going out both sides. Any preference?

Question: Does my mylar streamer need wadding, or does my baffle satisfy that requirement?

If you have the space, I think the straw is better.

If you use the Estes TP sheet wadding, and again have the space, a single sheet wrapped burrito style around the chute or streamer is always good insurance even with a baffle. ymmv

 

[SharkWhisperer]

I've pleated my streamers, and am now contemplating the attachment method. The simplest seems to be a knotted line held in tape going out one side. I've seen another with a taped on soda straw providing for a line going out both sides. Any preference?

Questions: Does my mylar streamer need wadding, or does my baffle satisfy that requirement? When not in use, should the streamer be stored in the tightly pleated condition, or in the expanded condition?

Do you have a pic of your baffle? Haven't really described it. A single baffle might allow hot particulates through. Material? Hole #/size/pattern? I always use two baffles--one right above the motor mount and another (with a different pattern) farther down (depending on accessibility into the body tube. Mylar is definitely heat-susceptible. For max flutter, wherever you attach it you might want to attach it off-center (i.e., not right at the 3.5" mark on a 7" wide streamer, to get more whip/drag. Grab one in both places and whip it around and see if there's a noticeable difference. If you have only a single baffle, or winged it on the design by intuition, I'd for sure use paper protection wrapped around your streamers. Just in case. Well designed baffles exist to remove the need for wadding/dog barf. Poorly designed ones will burn your laundry and kill rockets.

 

[Dotini]

Do you have a pic of your baffle? Haven't really described it. A single baffle might allow hot particulates through. Material? Hole #/size/pattern? I always use two baffles--one right above the motor mount and another (with a different pattern) farther down (depending on accessibility into the body tube. Mylar is definitely heat-susceptible. For max flutter, wherever you attach it you might want to attach it off-center (i.e., not right at the 3.5" mark on a 7" wide streamer, to get more whip/drag. Grab one in both places and whip it around and see if there's a noticeable difference. If you have only a single baffle, or winged it on the design by intuition, I'd for sure use paper protection wrapped around your streamers. Just in case. Well designed baffles exist to remove the need for wadding/dog barf. Poorly designed ones will burn your laundry and kill rockets.

This old man has no pix yet. Hopefully I'll get them to you before the next Ice Age. My Bertha baffle is an Apogee kit. A wide ring of holes on one end, a different, narrow ring on the other. You can partially see through it - very dubious! I will wear belt and suspenders and use burrito-wrap wadding with this one.

You know, I'm sure, pleating 90" of mylar at 0.5" per pleat is a fairly, uh, tranquil task, to put it mildly. Especially when you have arthritis. So I've ordered a crimping roller device and a roll of tracing paper. For my next conventional rocket, I will use two paper streamers, 8.5" x 40", one black the other white. This oughta be an even better fire-hazard, so again, belt and suspenders, baffle and barf. But I'll be having a baffle I can't see through.

Many thanks for all the help I'm getting at this excellent forum!

 

[dhbarr]

This old man has no pix yet. Hopefully I'll get them to you before the next Ice Age. My Bertha baffle is an Apogee kit. A wide ring of holes on one end, a different, narrow ring on the other. You can partially see through it - very dubious! I will wear belt and suspenders and use burrito-wrap wadding with this one.

You know, I'm sure, pleating 90" of mylar at 0.5" per pleat is a fairly, uh, tranquil task, to put it mildly. Especially when you have arthritis. So I've ordered a crimping roller device and a roll of tracing paper. For my next conventional rocket, I will use two paper streamers, 8.5" x 40", one black the other white. This oughta be an even better fire-hazard, so again, belt and suspenders, baffle and barf. But I'll be having a baffle I can't see through.

Please let us know on the crimping roller, been meaning to get around to trying that out.

 

[Dotini]

Please let us know on the crimping roller, been meaning to get around to trying that out.

Absolutely, yes!

 

[SharkWhisperer]

This old man has no pix yet. Hopefully I'll get them to you before the next Ice Age. My Bertha baffle is an Apogee kit. A wide ring of holes on one end, a different, narrow ring on the other. You can partially see through it - very dubious! I will wear belt and suspenders and use burrito-wrap wadding with this one.

You know, I'm sure, pleating 90" of mylar at 0.5" per pleat is a fairly, uh, tranquil task, to put it mildly. Especially when you have arthritis. So I've ordered a crimping roller device and a roll of tracing paper. For my next conventional rocket, I will use two paper streamers, 8.5" x 40", one black the other white. This oughta be an even better fire-hazard, so again, belt and suspenders, baffle and barf. But I'll be having a baffle I can't see through.

Many thanks for all the help I'm getting at this excellent forum!

Sounds like a lotta work and expense. Baffles should work pretty well on their own, but a wrap of wadding is good insurance. There's going to be light passage through both baffle disks at various angles--gasses gotta get through there, too. You'll be low enough that you can retrieve it and check the wadding for any char/burn marks. If none--no wadding needed. Me? I'd slap a parachute on it and call it done. Flammable tracing paper for streamers...yipes. I'd use the cheap Chicom stuff from the Dollar Store before anything overtly flammable. No way that bird will escape you on a parachute and B-motor altitude with short delay unless you're launching it in a super super small opening. Probably the safest and most proven method for low-level Bertha retrievals. Then you can mess around with streamer recovery. That's already a heavy bird for streamers, even two streamers (that might tangle one another), and a first flight probably isn't the best time for experimenting. Please consider just slapping a chute on that girl, on a fishing snap-swivel for easy on/off. Minimal wind and a straight (low) flight and she'll probably land right at your feet. Then you can experiment with streamers at leisure? Tracing paper? Argh. Flammable and prone to tearing. Not sure which quality is worse.

 

[Dotini]

Sounds like a lotta work and expense. Baffles should work pretty well on their own, but a wrap of wadding is good insurance. There's going to be light passage through both baffle disks at various angles--gasses gotta get through there, too. You'll be low enough that you can retrieve it and check the wadding for any char/burn marks. If none--no wadding needed. Me? I'd slap a parachute on it and call it done. Flammable tracing paper for streamers...yipes. I'd use the cheap Chicom stuff from the Dollar Store before anything overtly flammable. No way that bird will escape you on a parachute and B-motor altitude with short delay unless you're launching it in a super super small opening. Probably the safest and most proven method for low-level Bertha retrievals. Then you can mess around with streamer recovery. That's already a heavy bird for streamers, even two streamers (that might tangle one another), and a first flight probably isn't the best time for experimenting. Please consider just slapping a chute on that girl, on a fishing snap-swivel for easy on/off. Minimal wind and a straight (low) flight and she'll probably land right at your feet. Then you can experiment with streamers at leisure? Tracing paper? Argh. Flammable and prone to tearing. Not sure which quality is worse.

Work and expense is not a problem for me.

Your advice is unquestionably sound. But I'm bent on a personal mission of low altitude, easy recovery, and philosophical divorce from parachutes. If I never see one again, it'll be too soon. Really I'd like to dispense with streamers as well. I'm embarked on a plan of experiments with die Glock, a series of ringtail odd rocs which seek to utilize a form of tumble recovery in which the model levels out and stalls, over and over again.

 

[SharkWhisperer]

But I'm bent on a personal mission of low altitude, easy recovery, and philosophical divorce from parachutes. If I never see one again, it'll be too soon.

Well have at it then. Determination is a powerful trait. Your deep dislike of parachutes is very entertaining.

If you soak those tracing paper sheets in a saturated solution of either sodium borate (Borax washing powder) or sodium bicarbonate (Baking Soda), and hang 'em up to dry then you'll have made them fire resistant. Estes wadding is just cheap single-ply TP soaked in sodium borate (probably with a little boric acid, too, to get more into solution) and dried and sold for 7 cents/square, hah ha!

I would never overpay for commercial wadding, except for those that come along with some of the 18mm Estes bulk motor packs that I buy (super cheap at AC Supply!). I'd use a couple of lettuce leaves from my refrigerator first (works well, btw).

Please don't make streamers out of untreated tracing paper--even if your baffles stop burning particulates, there's still a super hot flame front and hyper-heated gasses that your laundry must contend with. Baffles cool that gas front by impeding it slightly, but not all that much. Don't forget that the theoretical max burn temp of BP is around 2350C (4260F for us Mericans); that's pretty hot stuff!

Attached is a US Army review of BP characteristics, for those interested.

 

[Dotini]

Well have at it then. Determination is a powerful trait. Your deep dislike of parachutes is very entertaining.

If you soak those tracing paper sheets in a saturated solution of either sodium borate (Borax washing powder) or sodium bicarbonate (Baking Soda), and hang 'em up to dry then you'll have made them fire resistant. Estes wadding is just cheap single-ply TP soaked in sodium borate (probably with a little boric acid, too, to get more into solution) and dried and sold for 7 cents/square, hah ha!

I would never overpay for commercial wadding, except for those that come along with some of the 18mm Estes bulk motor packs that I buy (super cheap at AC Supply!). I'd use a couple of lettuce leaves from my refrigerator first (works well, btw).

Please don't make streamers out of untreated tracing paper--even if your baffles stop burning particulates, there's still a super hot flame front and hyper-heated gasses that your laundry must contend with. Baffles cool that gas front by impeding it slightly, but not all that much. Don't forget that the theoretical max burn temp of BP is around 2350C (4260F for us Mericans); that's pretty hot stuff!

Attached is a US Army review of BP characteristics, for those interested.

Back in the 60's I got involved in sports car racing, and needed a fire resistant jacket to race under SCCA rules. I made my own by soaking my London Fog in a borax solution. I'll do that with my tracing paper, too.

 

[tsmith1315]

Back in the 60's I got involved in sports car racing

If you have pictures, we'll be needing to see those!

 

[Dotini]

Karting at Bremerton, Washington, about 15 years ago. The number 1 indicates I was the reigning national champion in my class that year.

Karting in the rain at Portland. Another configuration. Notice expansion chamber enclosed within body. Unique design with stinger located middle of chamber.

Kart race at Reno, Nevada

 

[Ronz Rocketz]

This old man has no pix yet. Hopefully I'll get them to you before the next Ice Age. My Bertha baffle is an Apogee kit. A wide ring of holes on one end, a different, narrow ring on the other. You can partially see through it - very dubious! I will wear belt and suspenders and use burrito-wrap wadding with this one.

You know, I'm sure, pleating 90" of mylar at 0.5" per pleat is a fairly, uh, tranquil task, to put it mildly. Especially when you have arthritis. So I've ordered a crimping roller device and a roll of tracing paper. For my next conventional rocket, I will use two paper streamers, 8.5" x 40", one black the other white. This oughta be an even better fire-hazard, so again, belt and suspenders, baffle and barf. But I'll be having a baffle I can't see through.

Many thanks for all the help I'm getting at this excellent forum!

I used the circle of hole baffle in the SWAT/Satellite Interceptor and worked surprisingly well with no burn marks on the chute.

I bought the Apogee Diamondback which has a large 4” wide silver streamer so I’ve been switching my small and medium rockets to 2” streamers I bought in a roll.

 

[Dotini]

Some of you guys wanted to see my rockets, so here they are.

 

[tsmith1315]

Cool kart pic's!

I dig the big B&W rocket, and your tumblers, too!

 

[Dotini]

This I call the Monogamist, since there's only one motor that will make it fly, the "Super" C5-3.
It's got linen skinned fins and a baffle. It's was fun to build. Next step with this is a swing test.

That red/yellow/blue model I think will fly on no fewer than 8 motors, so I call that one the Bigamist.

 

[BABAR]

Some of you guys wanted to see my rockets, so here they are.

View attachment 454327

Wow, nice little fleet.
Bertha passes the eyeball test, looks like an extremely stable rocket assuming you can get it off the rail with normal velocity. You may want to try ThrustCurve.Org. I liked (And still like!) the idea of a swing test......but while a swing test will tell you if the rocket is aerodynamically stable, the presumption is that the thrust to mass relationship is also adequate. biggest fins in the world won’t help you if the velocity is insufficient to get enough air flow to get them effective before the rocket leaves the rod or rail.

I like your stick and tube fin models. how do they fly? Does the motor plume stain the tubes? They do seem a bit lacking in space for recovery gear, but I am wondering if with those big tubes in the back they recovery horizontal with just small streamers out the nose?

 

[Dotini]

View attachment 454419
Wow, nice little fleet.
Bertha passes the eyeball test, looks like an extremely stable rocket assuming you can get it off the rail with normal velocity. You may want to try ThrustCurve.Org. I liked (And still like!) the idea of a swing test......but while a swing test will tell you if the rocket is aerodynamically stable, the presumption is that the thrust to mass relationship is also adequate. biggest fins in the world won’t help you if the velocity is insufficient to get enough air flow to get them effective before the rocket leaves the rod or rail.

I like your stick and tube fin models. how do they fly? Does the motor plume stain the tubes? They do seem a bit lacking in space for recovery gear, but I am wondering if with those big tubes in the back they recovery horizontal with just small streamers out the nose?

Thanks! These are the first models I've built in 30 years.

I've been building this little fleet since New Year's Day, and haven't flown anything yet. The weather is just now getting good, and I will launch this week - hopefully.

The stick and tube models are for experiments in tumble recovery. I begin to get into detail on this down in the Odd Rocs thread.

 

[Dotini]

Today I'm very happy to report my first rocket launch in 30 years!

This morning at Carkeek Park, Blair and I launched 5 out of the fleet of eight models I've built this winter. All launches were succesful, no models were damaged, and important lessons were learned and/or relearned. And we had fun. Blair chuckled uncontrollably when we launched the Blender.




From left to right: Bigamist (B4-2), custom-finned Big Baffled Bertha (B6-2), die Glock (1/2A6-2), Blender (A10-0T), Animist (1/2A3-2T)

I think the Animist went highest, and also came down closest to the launch pad.

 

[boatgeek]

Today I'm very happy to report my first rocket launch in 30 years!

This morning at Carkeek Park, Blair and I launched 5 out of the fleet of eight models I've built this winter. All launches were succesful, no models were damaged, and important lessons were learned and/or relearned. And we had fun.



View attachment 454766
From left to right: Bigamist (B4-2), custom-finned Big Baffled Bertha (B6-2), die Glock (1/2A6-2), Blender (A10-0T), Animist (1/2A32-T)

Hi Neighbor! (I'm in the north end of Ballard)

The Carkeek field is nice, but a little small and surrounded by rocket-eating trees. If you can spare a bit of time to go to the east side, 60 Acres Park is the best field in the area. As advertised, 60 acres of soccer fields, all empty now (Thanks, COVID!). Most any weekend with nice weather, there'll be a few people there launching rockets from 1/2A to G or so.

 

[Dotini]

According to Estes catalog Launch Site Dimensions chart, a field 100' square is enough for A type motors and 400' altitude. They say a 200' square is okay for B type engine and 800'. I'd say that's too generous.

Carkeek is a disused line control model airplane field, a circle 200' diameter, with trees encroaching. In my humble opinion, 200' is about the right maximum altitude for Carkeek, and I don't think any of my rockets exceeded that altitude.


Carkeek Park, 100' to the nearest tree, a lush Puget Sound view, and a ten minute drive. Do not bring a parachute; streamer or tumble/spin works best here.

 

[boatgeek]

According to Estes catalog Launch Site Dimensions chart, a field 100' square is enough for A type motors and 400' altitude. They say a 200' square is okay for B type engine and 800'. I'd say that's too generous.

Carkeek is a disused line control model airplane field, a circle 200' diameter, with trees encroaching. In my humble opinion, 200' is about the right maximum altitude for Carkeek, and I don't think any of my rockets exceeded that altitude.

View attachment 454772
Carkeek Park, 100' to the nearest tree, a lush Puget Sound view, and a ten minute drive. Do not bring a parachute; streamer or tumble/spin works best here.

I think my tone came off wrong in my last post--I wasn't trying to say Carkeek is a bad place to launch*, just that if you want to stretch altitudes a bit more or if you find yourself losing rockets in trees, 60 Acres is a great alternative. We've spent a lot of time at Carkeek as our kids were growing up, though mainly on the north side and the beach. It's a beautiful place.

* Although at first I envisioned you launching on the upper field by the playground. That seemed a bit bold.

 

[neil_w]

200' square is mighty tight. I've launched on a nearby 400' square field and it was dicey with A motors.

 

[BABAR]

Today I'm very happy to report my first rocket launch in 30 years!

This morning at Carkeek Park, Blair and I launched 5 out of the fleet of eight models I've built this winter. All launches were succesful, no models were damaged, and important lessons were learned and/or relearned. And we had fun

I think the Animist went highest, and also came down closest to the launch pad.

First, congrats.

second, sounds like a great launch, especially if lessons were learned (added bonus.). Although after safety, having fun is most important factor in any model rocket launch!

third, I thought you said Animist had no recovery system? If it had no recovery system, no mystery if it landed closest to the pad!

 

[BABAR]

If you are good with your hands at fine detailed work (and your rockets show nice craftsmanship, I have nothing that looks as good as yours, except maybe my Interceptor E and I cheated with vinyl skins) MicroMaxx rockets might also be an excellent small field option. It’s almost a backyard option for some of them.

 

[Dotini]

First, congrats.

second, sounds like a great launch, especially if lessons were learned (added bonus.). Although after safety, having fun is most important factor in any model rocket launch!

third, I thought you said Animist had no recovery system? If it had no recovery system, no mystery if it landed closest to the pad!

I meant to say the Animist's recovery system was "unacceptable", consisting only of clay reinforcing in the nosecone and a lucky landing in a mud puddle.

 

[BABAR]

BTW, nice to see your Big Bertha modified flew and recovered without damage. Was that on the big streamer? Did it land on the casing?

 

[Dotini]

BTW, nice to see your Big Bertha modified flew and recovered without damage. Was that on the big streamer? Did it land on the casing?

Yes, the modified Big Bertha flew, albeit poorly, and landed on soft, grassy soil without any trace of damage. It carried two well pleated mylar 6" x 48" streamers which deployed perfectly. It was on a B6-2 but seemed to pass apogee at low (under 200') altitude before ejection. I built it too heavy and draggy. The fins I put on are too long and have wide, flat, square edges. I need to shorten up the fins and round the edges before flying her again. Putting a baffle in it was a mistake that I can't easily fix. I consider it a beginner's learning effort.